This invention relates to a method of and an apparatus for activating a plurality of groups of electrical loads such as electrically activated detonators. The invention has particular application in surface blasting techniques.
When carrying out a blasting operation on the surface of, for example, a quarry, the area of the blast may be very large. For example, an area of 500 m by 60 m (30 000 m.sup.2) may be covered. This area may have, say, 300 holes, with multiple detonators per hole if the decking principle is used.
If electronically controlled detonators are used, the total length of the harness wires required to control the blast may be several kilometers. This can cause problems in powering and synchronizing all of the delay devices. Given the fact that the value of the explosive used in such a large blast may be of the order of several hundred thousand rand, it is very important to maintain timing accuracy when carrying out such blasts. It is also important to maintain safety standards in such blasts.